Method and means for emitting sig



22. 9 E. R. PARSBERG 2,219,018

METHOD AND MEANS FOR EMITTING SIGNALS WITH VARYING SIGNAL CHARACTER Original Filed Dec. 22, 1932 INVENTQR v i2 en/Pa r'ae ry,

BY %44 .HTTORNE) Patented Oct. 22, 1940 PATENT OFFICE METHOD AND MEANS FOR EIWI'ITING SIG- NALS WITH ACTER VARYING SIGNAL CHAR- Erik Robert Parsberg, Lidingo, near Stockholm, Sweden, assignor to American Gas Accumulator Company, Elizabeth, N. J., a corporation of New Jersey Original application December 22, 1932, Serial No.

December 24, 1931 7 Claims.

Application for Letters Patent was flied in Sweden December 24, 1931, and in the United States December 22, 1932, Serial No. 648,348. The present application is a division of United States application Serial No. 648,348, on which Patent No. 2,096,755 issued October 26, 1937.

It has become the general practice in arranging the illumination of air routes to use powerful revolving searchlights projecting beams of condensed light which sweep the horizon. When these beams of light sweep past a certain point, the impression obtained in the said point is that of a flashlight character, usually single flash. The period between the separate flashes varies in length in different countries. In America, for instance, it is considered sufficient with one flash every ten seconds, whereas in Germany they have generally gone in for a period of about three seconds. If it is taken into consideration that it 23 has been the practice for years to provide one flash every flve seconds for marine trafflc, which moves much slower, the conclusion is easily arrived at that for aviation the period should be quicker and not slower, and consequently that a period of three seconds would be more in accordance with the requirements of air traflic.

Flashes at shorter intervals may be obtained by increasing the rotary speed of the apparatus or by dividing the available light energy into several beams. In both cases the efliciency of the beacon will be reduced. In the first case the light impression will be diminished owing to the reduced duration of the flash (according to the Blondel and Rey law), while in the latter case the light efliciency of the beacon will be reduced by the division of the light energy.

The Frenchmen Blondel and Rey have scientifically proved that, in order to obtain a flashlight of a light range equivalent to that of fixed light, the light power of the flashlight must be larger and consequently, in order to express its equivalent in terms of a flxed light, the light power of a flashlight must be multiplied by a factor which is less than 1. This factor is dependent on the duration of the flash and diminishes quickly as this is reduced. The factor in question is, for instance, approximately .2 for a flash of .03 second, .48 for a flash of .1 second, and rises to .84 for a flash of .3 second.-

From this point of view, it would be advantageous in order to obtain a good light impression or a good signal effect, to have a long duration of the flash, which can be attained by increasing the width of the light beam or by reducing the rotary speed of the beacon. From Divided and this application September 30', 1937, Serial No. 166,537.

In Sweden the point of view of light economy the first mentioned way of solving the question is not to be recommended. On the other hand, a reduction of the rotary speed will mean that the interval between the separate flashes will be longer. As

stated above, it is desirable that this interval 1 should be comparatively short.

It is evident that the two requirements which thus present themselves, particularly in the technique of airway beacons, i. e., long duration of the flash on the one hand and short intervals between the separate flashes on the other, are at variance with each other, inasmuch as compliance with one of the requirements requires a low rotary speed, whereas the other requires high rotary speed of the beacon.

This invention refers to an arrangement by means of which the above-mentioned features are both attained simultaneously, the lens or reflector system of the beacon being soarranged that the projected beam is divided into two parts that move in opposite directions simultaneously, either by rotation, or by oscillation over a predetermined angle with a revolving motion in such a way that the signal character of the beam or beams of light will be different in different directions. Preferably according to the invention the rotating lens or reflector system' of the beacon is not allowed to revolve uniformly, as has been the practice hitherto, i. e., with an approximately constant speed in the same direction, but is instead given a non-uniform revolving motion. By non-uniform revolving motion is to be understood in this connection that in certain sections of the revolution the system revolves at a slower speed than in other sections.

The intention with such a non-uniform revolving motion is to improve the light'impression in certain sections of the revolution at the expense of the light impression in the other sections. When the beacon is intended as an airway beacon, the flying direction is suitably laid through the first mentioned sections, because the beacon light should be most visible in that direct on, whereas the other sections do not as a rule be shorter in the other sections. A beacon having two lens panels arranged at an angle of 180 between their optical axis, and giving at a-con'- 'areat right angles to the flying direction will suecessively be reduced to about half.

Fig. 1 is a. light diagram illustrating a form of the invention in which two reflector devices are arranged with one above the other, both oscillating in the same angle in opposite directions;

Fig. 2 is a light diagram illustrating a similar form of the invention, where the two devices revolve in opposite directions at the same speed;

Fig. 3 is a diagrammatic illustration of two such devices revolving in opposite directions at different speed; and

Fig. 4 is a vertical sectional view of a form of apparatus for use in practicing the invention.

Fig. 1 shows a light diagram according to which'two lens or reflector apparatus placed, for instance, on top of or beside each other, move back and forth within the same angle but in opposite directions, as indicated by the light character curves 2 and z of the respective apparatus. Single flash with long flashes is obtained in the turning points a and 2 of the revolving motion, respectively, whereas a more or less pronounced double-flash is obtained between the turning points except at the centre of the angle, where single flash is obtained.

Similar forms of employing the invention with two diametrically opposite light sections are particularly well suited for airway beacons placed along coasts where no light is desired towards the sea. 1

Lights of the description in question make the use of special so-called "course lights unnecessary, because the aviator will notice an alteration in the flying character as soon as he deviates from the flying course.

The above described forms of arranging the light may naturally also be used for maritime beacons, or for maritime and airway beacons combined.

In the diagram shown in Fig. 2, two lens parts placed, for instance, ontop of or beside each other, revolve in opposite directions but at the .same speed. The light efficiency curve is shown at q, from which is seen that a very marked increase in the light range is obtained at a and q, in which points ofthe periphery the light beams from the two lens parts coincide. The curve r indicates the light character of one of the lens parts, while the curve a indicates the character of the other part. It .will be realized that double-flash is obtained everywhere except in the direction.tt, where the light beams from the two lens parts coincide and where a long single-flash character is obtained. In addition, a singleflash character twice as rapid is obtained in the direction tt at right angles to tt, but in that flying route, which issuitably laid in the direction tt, with.a deviation of a few'degrees onlyr because as soon as -he leaves the route, flying for instance to the right of it, he will notice a light beam coming from the right first, quickly followed plicated. The light character curve of one of the lens parts is represented by u, and the curve of the other lens part, by 0.

Referring to the apparatus shown in Fig. 4, the lens or reflector system is divided in two parts which may move in relation to each other, corresponding to the diagrams of Figs. 1, 2 and 3. Fig. 4 shows a lens apparatus cut in two halves by a horizontal plane through or near the focus of the lens system. The lower lens part 13 rests on the disk 64, placed on the vertical driving shaft 65. The upper lens part I4 is supported by the rods 66 which are secured to a table 61 revolving around the shaft 65. On the shaft 65 and the table, respectively, the conical cog-wheels 68 and 69 are arranged, which gear with a common conical cog-wheel Hi. If this latter cog-wheel is caused to revolve, the upper and the lower parts, 14 and 13, of the lens apparatus, will revolve in opposite directions. A periodically varying motion may simultaneously be obtained by connecting suitable driving mechanism to the shaft ll of the cog-wheel 10. As is shown, this mechanism consists in this case of an inclined universal joint.

By the said division of the lens one common source of light 5 may be used. This is advantageous both from an economic point of view and from the point of view of safety, as compared to the arrangement hitherto used in such cases of providing each part of the lens with a separate source of light. If in the latter case one of the two light sources should go out, the beacon would show a false character.

Obviously the method of transmitting directed beams, above mentioned, can be used in connection with beams of all kinds. Here the use of beams of visible light has been shown, but it is assumed that radio beams orbeams of other than visible light may be transmitted equally well in the same manner.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In route signaling apparatus, the combination of a source of radiant energy, separate projecting means for producing from said energy two beams independently movable substantially in the same plane, a rotatable support for each of said projecting means, and mechanism for rotating each of said supports to thereby swing said beams simultaneously across the route in opposite directions at pre-determined time intervals.

2. In route signaling apparatus, the combination of a source of radiant energy, separate projecting means for producing from said energy two beams independently movable substantially in the same plane, a support for each projecting means rotatable about a common axis, a driving shaft, and mechanism interconnecting said driving shaft and said supports to turn said supports in opposite directions to thereby move said beams simultaneously across the route in opposite directions at pre-determined time intervals.

3. In route signaling apparatus, the combination of a source of radiant energy, separate prosupports is fixed, a sleeve secured to the other of said supports and rotatable on said driven shaft, a driving shaft, a bevel gear secured on said driven shaft, a bevel gear secured on said sleeve, and a bevel gear on said driving shaft and intermeshing with the bevel gears on said driven shaft and said sleeve to turn said supports simultaneously in opposite directions upon actuation of said driving shaft.

4. A route beacon comprising a source of radiant energy, two superposed projecting means each for producing substantially in the same plane two oppositely directed beams from the energy emitted by said source, a rotatable support for each of said projecting means, and mechanism for turning said supports simultaneously in opposite directions.

'5. The method of'producing signals with different signaling character in different directions, comprising the production of two beams of radiant energy substantially in the same plane from the same source, and continuously rotating said beams in opposite directions around said source.

6. The method of producing signals with different signaling character in different directions, comprising the production of two beams of radiant energy substantially in the same plane from the same source and continuously rotating said beams simultaneously in opposite directions around said source at the same time interval.

'7. The method of producing signals with different signaling character in different directions, comprising the production of two beams of radiant energy substantially in the same plane from the same source, continuously rotating said beams in opposite directions at uniform time intervals and substantially decreasing the angular speed of each beam in a given direction during each rotation.

ERIK ROBERT PARSBERG. 25 

